Avista implemented “temporary unplanned power outages,” otherwise known as rolling blackouts, on Monday as temperatures reached a record-tying 105 degrees in Spokane and put a “strain on the electric system,” the utility said in a news release.
Nearly 5,700 Avista customers in parts of Spokane were without power as of 8:05 p.m., down from as many as approximately 8,200 earlier in the day.
And many more of the utility’s customers will likely see rolling outages Tuesday between 1 and 8 p.m., said Heather Rosentrater, Avista’s senior vice president for energy delivery, during a Monday night news conference.
Avista had plans for high loads on Monday, Rosentrater said, but the system hit its limit faster than expected.
“We planned for this,” she said. “We had the forecast.”
But she also suggested Avista was caught off-guard by the effect the extreme heat would have. The blackouts occurred on a day that reached 105 degrees, tying the record for hottest June 28 in Spokane history, according to the National Weather Service. The record was set in 2015.
“The temperatures that we experienced caused our system to react in a way that was unanticipated,” Rosentrater said. “We saw much more significant loads than we expected.”
Some experts anticipated that an unusually hot and dry summer would likely strain the Western power supply, with Washington expected to see a shortfall of hours totaling nine days.
Two primary factors contributed to the then-anticipated power shortfall, according to a Bloomberg report. First, climate change is making it harder to forecast demand for electricity. And second, the shift to clean energy is straining power supplies.
Recent data from the National Oceanic and Atmospheric Administration identified rising average temperatures in Spokane over the last decade, with July the month that has seen the sharpest rise. The average temperature is 1.2 degrees warmer in July in Spokane than it was a decade ago, researchers found.
Rosentrater said Avista would be better prepared going forward, though the company – and its customers – will have to deal with even more extreme heat.
“We learned a huge amount today based on the weather and the increased loads that we saw and we have a plan for tomorrow,” she said.
Rosentrater said Avista is planning to put in place on-hour outages over the course of Tuesday and intends to let people know ahead of time. She urged people to update communication preferences with the company so they receive notices of impending periods without electricity.
She said Monday’s outages were largely triggered by alarms on the power system that forced the utility to take immediate action.
On Tuesday, she said Avista will have lower thresholds to initiate smaller, targeted outages.
The problem, she said, is not the supply of power but rather constraints on the distribution system caused by heat and a high load as people pump their air conditioners and run fans.
On Monday, outages were first reported at approximately 1:45 p.m. in areas around the Nevada-Lidgerwood neighborhood, between East Hawthorne Road south to East Wellesley Avenue, according to Avista’s outage map. A total of 4,865 customers were affected as of 2 p.m.
Meanwhile, another outage was reported around 3:10 p.m. Monday in parts of West Spokane, stretching from around Spokane Falls Community College to the southern end of Latah Valley.
“As a state and federally regulated utility, Avista is required to reduce electric load on the system when certain system thresholds are met,” Casey Fielder, an Avista spokesperson, said in a statement. “In certain areas, these thresholds have been met rather quickly, and to meet the requirement, power has been turned off temporarily.”
With temperatures only expected to continue climbing on Tuesday, Avista asked people to conserve energy as temperatures are expected to continue exceeding triple digits this week .
Avista is calling for customers to reduce electricity use from 1 to 8 p.m. through Thursday. Similar conservation requests may follow as needed, Avista said in Monday’s announcement.
Representatives for the utility said the high temperatures are straining the electric system, which serves 400,000 customers across a 30,000-square-mile territory in Eastern Washington, North Idaho and parts of southern and eastern Oregon.
“Avista always works with our customers to use energy efficiently and to conserve energy where possible, and we will count on that partnership as we all manage through this heat wave together,” Dennis Vermillion, Avista’s president and CEO, said in a statement.
The Kootenai Electric Cooperative, which operates approximately 2,300 miles of electric line in parts of Kootenai, Benewah, Bonner and Spokane counties, has put out a similar call for customers to conserve energy. The company is encouraging measures such as postponing the use of appliances, such as washers, dryers and dishwashers, until after 10 p.m. and setting the thermostat on central air conditioning units to 78 degrees or higher.
Avista manages the system in the summer months by shifting electricity load to accommodate increased use in certain areas, according to Monday’s announcement.
The utility is advising customers to consider the following:
• Reduce the use of air conditioning and other large electrical appliances.
• Use a box fan to cool when possible.
• Reduce the use of heat-producing appliances, such as dishwashers, ovens, ranges and dryers.
• Keep drapes and blinds closed during the day.
• Use an outdoor barbecue grill.
• Use small electric appliances or a microwave instead of the stove or oven.
• Replace air conditioning filters frequently and make sure central air conditioning units are clear of debris.
Rosentrater described Monday as a learning experience.
“We have not experienced this kind of demand on our system and these kinds of impacts to our system,” Rosentrater said. “This is very unprecedented.”
Editor’s note: This story has been corrected to accurately reflect Bloomberg’s report citing reasons for the power shortfall.